This invention relates to the treatment of waste containing poisonous substances.
The term "waste" used herein includes solid industrial wastes such as sludge, slag and red mud as well as municipal refuse such as garbage and ash. The term "poisonous substances" means toxic or polluting materials including heavy metals such as cadmium, mercury, lead and arsenic, and sulfides, cyanides and organic phosphorus compounds as well as radioactive materials.
A number of techniques have been proposed to treat waste containing poisonous substances so as to prevent the poisonous substances from leaching out. Such techniques are basically classified into two methods. One method chemically renders poisonous metals insoluble using chelating agents such as EDTA and NTA. Insolubilization is not always complete and reaction conditions are restricted. Further, this method is expensive. Another method pertains to physical encapsulation of poisonous substances. Cement, concrete, asphalt, resin, or glass may be used. However, they are either expensive or insufficient in their confinement abilities.
The primary object of this invention is to process sludge into resin clad capsules so as to seal poisonous substances using a microwave technique wherein the capsules can be kept unchanged substantially eternally, and prevent poisonous substances from leaching or eluting when contacted with water, and allow the processed sludge to be bonded into a solid shape.
Another object of this invention is to manufacture articles from waste containing poisonous substances by encapsulating the waste particles with a resin and forming the capsules into an article which is suitable for use as building blocks, road pavements or undersea fish shelters.
A further object of this invention is to provide an economical method of treating sludge containing poisonous substances by encapsulating sludge particles with a resin wherein a waste thermoplastic synthetic resin may be used as the encapsulating resin.